1. Field of the Invention
The present invention relates to a disk device for recording an audio-visual signal on, and reproducing the audio-visual signal from, an optical disk, and a control method therefore, and relates particularly to a disk device that can appropriately adjust the defocused positioning of an unrecorded disk, and a control method therefore.
2. Description of the Related Art
Conventionally, an audio-visual signal is recorded on an unrecorded disk while defocusing of an optical pickup is adjusted by referring, for example, to a predetermined fixed value. Thus, depending on the type of optical disk mounted in a disk device, defocusing of an optical pickup can not be appropriately adjusted, and since then the optical pickup can not record using a laser beam at its optimal recording power, the quality of the recorded audio-visual signal is deteriorated. Further, during a process for the recording of a test signal in a predetermined area on an optical disk, performed in order to correct the defocusing of an optical pickup, an optimal laser power can not be designated for the optical pickup, either because of the repetitive overwriting of test signals or because the quality of the audio-visual signal recorded on the optical disk is deteriorated.
There is a related art wherein a test signal is recorded by gradually changing the laser power employed for the recording of an optical disk, and the recording quality is calculated, by reproducing the test signal, to obtain for the defocused state of the optical pickup an offset value that is then used to correct the recording power of the optical pickup (see, for example, JP-A-2002-312939).
There is another related art wherein, when the image forming level of a reproduction laser beam, emitted by an optical pickup, is too high for the reproduction of a test signal recorded on an optical disk, the imaging forming level is reduced, and based on an asynchronism of the test signal, the recording laser power provided for the optical pickup is adjusted (see, for example, JP-A-2004-22084).
There is an additional related art wherein, when a predetermined amount of data has been recorded on an optical disk, the recording of data is halted, the state wherein data are being recorded on the optical disk is examined, and the laser power to be provided for the optical pickup, for subsequent recording, is determined (see, for example, JP-A-2004-234812).